Method of removing insulating coatings from wires



June 19, 1956 J. A. ORME 2,751,317

METHOD OF REMOVING INSULATING COATINGS FROM WIRES Filed June 3, 1950 INVENTOR. L/Zx/xv ,4. 09M! In ark 9 y United States Patent 5 ,317 Y METHOD ODE-REMOVING INSULATINGQGOATINGS FROM ahnA- 0. 7 19, Lss Anae es-C l t- Application June 3, 1950, Serial No. 166,005: s cnimsi (ctr-111123;).

llhisinvention relates toandhasforan object-theprovisionof aisimple and .efiective apparatus and-method for: removing insulating coatingfromwwires.

In modern electrical. practice, especially in the-production; ofjfinev wires .such. as. are. .used tor relays, "electromagnets and other purposes, enamel. coatings are -used for-. insulating the wires in .order that acoiI may-:b'e-formed wliichwill-be 0f..a..minimurn.size fora givenaoutputor function and. closely. wound. and yet adjacent windings completely: insulated .against short circuits. It :is necessary, howeyenthat terminal. portionsaof the wires,. and frequently intermediateportions ofsthe wires, be. stripped of theirginsulation. in order .to. provide. positive electrical connections 1 in a. system.

In such instances variousdevices and methodsv have been employed which while alfording desired results,

have required the use of cumbersome and more or less complicated apparatus, unnecessary expense and unjustifiable time. In some cases the insulated wires have been heated in ovens to an extent required for dissipation of the insulation, subjected to direct application of heat from a flame, or immersed in molten solder. While such methods may have merely sufiiced to remove insulation from the wires, none of them have been completely satisfactory and I have ascertained by protracted experimentation that such insulating coatings are readily removable by the use of an extremely simple expedient which does not require skilled operators and is very inexpensive.

In its broadest aspect my invention includes the use of a crystalline mineral substance acting as a soldering flux which when applied to an enamel insulated wire under direct heat from a presoldered iron simultaneously loosens the insulation and tins the treated section of a wire, while the insulation is loosened and removed. I have ascertained that sal-ammoniac meets the requirements of such a substance.

Another broad aspect of my invention includes the application of a hydroxide such as potassium hydroxide (KOH) or sodium hydroxide (NaOH) and heat to a section of wire from which it is desired to remove the insulation. But due to the peculiar properties of said elements, their susceptibility to and disintegration in the presence of moisture, they are difficult to handle and control. Hence it is an object to provide a simple apparatus which will support a cartridge of either of said elements under moisture proof conditions while at the same time rendering the hydroxide immediately available in necessary quantities to meet all demands of insulation removing operations and without possibility of contact with the moisture laden atmosphere.

To such end i have provided a miniature apparatus including a chambered base in which a cartridge of crystalline hydroxide is sealed by a suitable readily fusible wax out arranged at an opening of said chamber with a pervious closure which is always sealed with the wax except during an insulation removing operation when the Wax is fused by heat and allows the release of minute but sufiicient quantities of the hydroxide in the form of CC Patented J 2. fin e aas if tac an the u t n mat n s wires .w hich pverlie the pervious closure.

3 swam n a h ss f heat d .placedl uponv the wire and theheattherefrom fractiireseor loosensv the insulatingcoating. of the wirle so. .that .the.. chemicals released from the cartridge will e-through the. fiuid. wax and closure and.v

h astu es a or nte b th th issslafls .ddistqdaaand.d ipat hapar islescti at tergalfrpm .the. wirewithout necessity: of stnpprpg; except w th-aclq hsrbru A er ob ect i810. p vi e mean r fsrsinsfibe .vss ar das ower. e pp firm por in theperv s asu et t I. aa ba ta d anima sas s1 win at sai membe f t essa t e snee eflt- 9 13: ma b m v d as e laes rand st'he d wsalss a iti n s tswds st l sha be t q preventing entrance of moisture to the champ which X 69 d-- t h n e t e h drsx de from aasrxst l 0.. ..fiu 1 s atei Othe 1. t pne a thea esa i ti a q rmy- Avt rth r: oldest ism .PIQViFl? emea ssa-ths base t isr saa s sst vs i w- Pt-at n ta l a patat showing an end portion -.o1".;a-.yyir,e-pos,; ipne thereongfor treatment by my method; v i

Fig. 2 is a vertical elevation of a section of the apparatus;

Fig. 3 is a top plan view of the same;

Fig. 4 is a sectional plan on line 44 of Fig. 2;

Fig. 5 is a fragmentary section of wire with insulated covering before treatment; and

Fig. 6 is a similar view of a wire showing a portion thereof after removing the insulation therefrom.

In its simplest form I am able to practice the invention by the provision of a base B formed of vitreous or heat resistance material, a cartridge C mounted in a bore 2 of the base, a pervious closure D mounted at the top of bore 2 beneath a narrow inwardly projecting flange 3 and overlying cartridge C and a spring S compressed between the lower end of cartridge C and a retaining disc E held inwardly of an internal annular flange 4 at the bottom of the base. The cartridge C is formed of a crystalline sal ammoniac or potassium hydroxide (KOH) or sodium hydroxide (NaOH) and when a hydroxide is used has a coating of fusible wax F over its periphery and also over its upper end adjacent screen D and lower end. The retaining disc B may be also sealed in its position with wax therebelow and within the shallow chamber 5 of the base so that moisture from the atmosphere cannot enter the bore 2 from any point and cause the disintegration of the cartridge C.

When a unit is formed, as shown in Figs. 1 and 2, in an upright position upon a supporting surface, a wire W, which is insulated with an applied enameled coating, is laid with the terminal portion upon screen D adjacent to an inorganic chemical flux and a hot iron, such as a presoldered iron G, is laid upon the terminal portion of the wire and serves to melt the wax coating F of the top and apply heat to the cartridge C and thereby release an inorganic chemical fiux such as sal ammoniac or hydroxide in the form of vapor or liquid for attack upon the terminal portion of the wire. The heat from iron G expands and fractures or at least loosens the enamel coating on the portion of the wire being treated and per- Q mits the entrance of the hydroxide vapor or liquid under the coating so that it may be readily wiped off with a brush or cloth leaving the terminal portion of the wire completely stripped of its insulation.

It is apparent that as the quantity of chemical in the cartridge is depleted by frequent use, the tension of spring S urges the cartridge C into contact with the screen so that the upper end of the cartridge is always adjacent said screen until the cartridge has been completely used.

The wax coating over the top of the cartridge, upon removal of iron G, flows back over the screen and seals the orifices therein so as to exclude moisture until heat again is applied upon another wire stripping operation.

An advantage of my apparatus and method is in the fact that the sal ammoniac or hydroxide serves as a flux which facilitates cohesion between the solder and the wire so that so-called tinning of the wire is accomplished in the same operation required to strip the insulation therefrom.

" The essence of the invention, therefore, is the provi- 'sion of simple, convenient and economical means for stripping insulating enamel from sections of wire by the simultaneous application of heat for loosening the enamel and a suitable flux to the treated portion of the wire for so loosening the enamel that it may be readily wiped off.

- I claim:

1 l. A method of removing insulating enamel from wire which comprises placing a portion of a wire to be denuded of enamel adjacent to a solid inorganic soldering flux, and applying a hot metal member to said wire in order to loosen the enamel coating on said wire and to apply heat to said flux so as to cause said flux to loosen said enamel.

- 2. A methed as defined in claim 1 wherein said inorganic flux is potassium hydroxide.

organic flux is sodium hydroxide.

4. A method as defined in claim 1 wherein said inorganic flux is sal ammoniac.

5. A method for removing insulating enamel from a portion of a wire and tinning said portion of said wire which comprises placing a portion of a wire to be denuded of enamel adjacent to a solid inorganic soldering flux, and applying a hot presoldered iron to said portion for loosening and removing the enamel from said portion of said wire, and applying solder to the treated portion of the wire simultaneously with the removal of said enamel. 1

References Cited in the file of this patent UNITED STATES PATENTS 1,065,401 Spitz June 24, 1913 1,344,664 Wander June 29, 1920 1,355,976 Howlett Oct. 19, 1920 1,714,879 Lang May 28, 1929 1,726,100 Da Costa Aug. 27, 1929 1,923,828 Janota Aug. 22, 1933 2,169,098 Howe Aug. 8, 1939 2,192,056 Watts Feb. 27, 1940 2,374,926 Fink May 1, 1945 2,421,617 Holmes June 3, 1947 2,432,868 Earl Dec. 16, 1947 2,435,239 Schub Feb. 3, 1948 2,462,127 Pheazey Feb. 22, 1949 2,505,627 Pessel Apr. 25, 1950 2,563,417 Pessel Aug. 7, 1951 2,572,956 Servis Oct. 30, 1951 

5. A METHOD FOR REMOVING INSULATING ENAMEL FROM A PORTION OF A WIRE AND TINNING SAID PORTION OF SAID WIRE WHICH COMPRISES PLACING A PORTION OF A WIRE TO BE DENUDED OF ENAMEL ADJACENT TO A SOLID INORGANIC SOLDERING FLUX, AND APPLYING A HOT PRESOLDERED IRON TO SAID PORTION FOR LOOSENING AND REMOVING THE ENAMEL FROM SAID PORTION OF SAID WIRE, AND APPLYING SOLDER TO THE TREATED PORTION OF THE WIRE SIMULTANEOUSLY WITH THE REMOVAL OF SAID ENAMEL. 